1. Field of the Invention
The instant disclosure relates to a radio frequency identification (RFID) device; more particularly, to a RFID device having metallic tubes for replacing the printed circuit board (PCB)/circuit components.
2. Description of Related Art
A conventional RFID system typically adopts a dipole antenna, which may be constructed to have vertical or horizontal polarization. The dipole antenna normally includes a printed circuit board (PCB). A pair of transformers is disposed on the PCB to generate a Balun area, and a resonance is generated between different polarities.
The operating bandwidth of the RFID is region-based. For example, the operating bandwidths in the U.S. and Europe are 902-928 MHz and 865-869 MHz, respectively. The different settings imply a distinct antenna structure of the RFID must be designed for each region. Such practice is not cost effective and is not suitable for mass production.
To address the abovementioned issues, the inventor has previously introduced a RFID antenna structure, as taught in the Taiwan Pat. No. M391736. The antenna structure comprises a metallic plate and a PCB. The PCB includes a pair of transformers for generating a Balun area. The metallic plate is a dipole antenna resonant to the vertical and horizontal polarizations. The transformers are connected to respective matching circuits, where the matching circuits are replaced according to the operating bandwidth of the RFID system. Thus, the antenna structure is serviceable for various operating bandwidths.
However, the inventor believes there are still rooms for improvements for the antenna structure of the RFID taught by the Taiwan Pat. No. M391736 (e.g., further cost reduction).
To achieve the abovementioned improvement, the inventors strive via industrial experience and academic research to present the instant disclosure, which can provide additional improvement as mentioned above.